Process for enriching a liquid with a gas and enriched product

ABSTRACT

A liquid enriched with a high concentration of gas, in particular, water enriched with oxygen, is produced by mixing the gas and liquid in an overpressurized system using a series of pressure reduction containers which sequentially reduce the pressure on the gas-enriched liquid in a slow incremental fashion, thereby allowing a high concentration of the gas to be maintained within the liquid phase.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of allowed application Ser. No.09/161,720, filed Sep. 29, 1998, now U.S. Pat. No. 6,105,942, herebyincorporated by reference in its entirety, which was acontinuation-in-part of application Ser. No. 09/057,553, filed Apr. 9,1998, now U.S. Pat. No. 6,059,270, hereby incorporated by reference inits entirety. These applications are related to German applicationnumber 197 49 202.4, filed Nov. 6, 1997, and 198 27 613.3, filed Jun.20, 1998, the subject matter of which is hereby incorporated byreference in its entirety.

FIELD OF THE INVENTION

The invention relates to a liquid enriched with an extraordinarily highconcentration of a gas phase component, and in particular, to waterenriched with a high concentration of oxygen gas. The invention furtherrelates to a method of enriching a liquid with a gas so as to obtain ahigh concentration of the gas within the liquid. In particular, theinvention relates to a method of enriching water with a high level ofgaseous oxygen. The invention further relates to apparatuses forenriching a liquid with a high concentration of a gas, and inparticular, for enriching water with an elevated concentration ofgaseous oxygen.

BACKGROUND OF THE INVENTION

It is known that all of the vital functions contributing to the humanmetabolism require oxygen, and that it is necessary for the humanorganism to obtain sufficient oxygen through breathing. However, methodshave been developed for purposefully supplying the human organism withan amount of oxygen in addition to that obtained through breathing. Suchadditional oxygen can be supplied for generally improving normalfunction and wellbeing, on the one hand, but can also be usedparticularly as a treatment, or as a supplement to treatments for sickindividuals. To accomplish this, it is known to use enriched water, thatis, water enriched with free, gaseous oxygen.

In one known method of enriching water with gaseous oxygen, oxygen gasis supplied to water via a perlite disposed on the bottom of an opencontainer that is filled with water. Perlite is a porous volcanicmineral. The oxygen is forced through the perlite at low pressure andbubbles through the water in the container before subsequently escapinginto the environment or the atmosphere at the liquid-air interface.Passing the oxygen through the water causes it to be enriched withoxygen. As a result of this enrichment, the concentration of “free”oxygen in the water is about 35 mg/L. The term ‘free’, as it is usedhere with respect to the oxygen gas, and throughout this applicationwith respect to free gas, is meant to include gas molecules which arereleased within the liquid phase as their physical interactions withliquid molecules in the fluid are broken.

This known method has some drawbacks, however. For example, theconcentration of free oxygen obtained in the water is only about 35mg/L, which is a relatively low amount. Furthermore, after bubblingthrough the liquid, a portion of the supplied oxygen escapes into theatmosphere and cannot be reused, thereby resulting in a high gasconsumption for the amount of oxygen-enriched water that is actuallyobtained.

While there may be beneficial effects to the human organism of usingwater enriched at the known, relatively low concentrations describedabove, better treatment results could be obtained if higher levels ofoxygenation could be achieved. Further, if less oxygen were lost to theatmosphere, the costs of producing oxygen-enriched water could bereduced.

Besides use for human consumption, for general well being and intherapeutic methods as referred to above, oxygen enriched water hasother known uses, such as in water purification processes, cleaningprocesses, and the like. Further, it may be desirable to enrich otherliquids with other gases for other uses, at higher concentrations thanare currently achievable, and with less wasted gas during the process ofenrichment.

As discussed above, therefore, a need has existed for water more highlyenriched with oxygen, a method of achieving the higher enrichment, andan apparatus for achieving the higher enrichment. A need has furtherexisted for other liquid gas-enriched products, as well as a method andapparatus for producing them.

SUMMARY OF THE INVENTION

It is a principal object of the present invention to meet theabove-described needs and overcome the above-described drawbacks of theprior products, methods, and apparatus.

In that regard, it is an object of the invention to provide an enrichedfluid comprising a liquid phase having dispersed therein a highconcentration of a gas phase component that is maintained within theliquid under normal storage conditions. In this enriched liquid, theconcentration of free gas is over 60 mg/L. In particular, the liquidphase is water, and the gas phase component is oxygen.

It is also an object of this invention to provide a method for enrichinga liquid with gas such that the liquid has a high concentration of freegas, while simultaneously reducing the amount of gas consumed in theprocess of enrichment.

It is a further object of the invention to provide an apparatus forenriching a liquid with a gas such that the liquid has a highconcentration of free gas, and gas consumption is reduced.

It is also a particular object of the invention to provide a method andan apparatus for producing water enriched with a high concentration ofoxygen gas, this concentration being higher than those previouslyachieved in the art, while simultaneously reducing the amount of oxygenconsumed.

The objectives stated above are accomplished in accordance with theinvention by first enriching a liquid with a gas in a closedoverpressure system, and following the enriching of the liquid, abruptlyexpanding the gas-enriched liquid by subjecting it to an abrupt drop inpressure. In the invention, because the gas is supplied to the liquid ina closed overpressure system, any excess gas is prevented from escapingfrom the liquid into the open atmosphere, and can be recaptured forsubsequent use in further enrichment of the liquid. According to afurther aspect of the invention, any excess gas that does not enrich theliquid during a first enriching process, remains inside the overpressuresystem, and can advantageously be reused at least once in the enrichingprocess.

Supplying the gas to the liquid under pressure effects an enrichment ofgas in the liquid. This enrichment occurs under high pressure, and isprimarily accomplished during the supply of gas to the liquid. The gasis maintained in the liquid by means of a close spatial connection orphysical “bond” between the molecules of the gas and the liquid.However, the high concentration of free gas in the liquid is notobtained merely by introducing the gas into the liquid. Rather, the highconcentration of free gas in the gas-enriched liquid is achieved bycreating a rapid drop in pressure, for example, by conducting thegas-enriched liquid out of the overpressure system into a lower pressurearea where abrupt expansion occurs. The gas-enriched liquid then expandsbecause of the lowered pressure. As the gas-enriched liquid expands, thegas molecules that were physically bonded to the liquid molecules in theoverpressure system are released. This release increases theconcentration of free gas in the liquid, e.g., free oxygen in water.

By using the novel practice of this invention, liquids enriched withconcentration of over 60 mg/L, and preferably, over 140 mg/L of free gasmay be obtained. Most preferably, the amount of free gas is over about200 mg/L. These concentrations were previously obtained using thegas-enrichment processes known in the prior art.

According to one embodiment of the invention, gas enriched liquid isconducted out of the closed overpressure system which can be selectivelyset to effect an accelerated, practically immediate expansion. Thisimmediate expansion generates an especially high concentration of freegas in the liquid. It has been determined that the rapidity of expansionand the attainable concentration of free gas are directly proportional,so that the faster the expansion, the higher the concentration of freegas that is obtained in the enriched liquid. Therefore, by setting therate of expansion of the gas-enriched liquid, the desired concentrationof free gas in the liquid may advantageously be selected.

According to another embodiment of the invention, the gas-enrichedliquid that is conducted away from the closed overpressure system isexpanded in a lower pressure system provided with an outlet, with apressure drop occurring along the path of this transfer due to thedifferent pressures dominating the overpressure system and the lowerpressure system. This lower pressure system comprises one or morepressure release vessels or containers in series, each having at leastone outlet. Where the lower pressure system comprises more than onepressure release vessel, the gas enriched liquid and headspace gas movefrom one vessel to another via the one or more outlets. As thegas-enriched liquid is conducted through this pressure drop, it expands,causing the gas in the liquid to be freed. The pressure ratios in theclosed overpressure system and the lower pressure system having theoutlet can be set, preferably so as to depend on one another. Forexample in a preferred embodiment, the pressure in the closedoverpressure system can be set in the range of about 1.5 to 6 bar, whilethe pressure in the lower pressure system having the outlet can be setin the range of about 0.2 to 2.5 bar. The pressures are set so that adistinct pressure drop occurs in the gas-enriched liquid moving betweenthe two systems, leading to an expansion of the liquid during which thegas is released.

In one aspect of this preferred embodiment of the invention, the liquidis moved from the closed overpressure system into a lower pressuresystem comprising a pressure release vessel having an outlet. During thetransfer, this lower pressure system is maintained at the same pressureas the pressure in the closed overpressure system. After this transferto the outletted vessel at a constant pressure, the pressure in thatcontainer is subsequently reduced in small increments. As a result,there is no rapid expansion of the fluid; rather it is allowed to expandin slow, incremental fashion. Once the liquid is moved to the pressurerelease vessel having an outlet, the pressure in that vessel is thendecoupled or cut off from the closed overpressure system with respect tothe pressure ratios between them, and the pressure in the lower pressuresystem is reduced slowly. In the process, the gas-enriched liquidexpands slowly.

During the slow expansion of the fluid, the gas is not liberated in theform of small bubbles inside the liquid to the same extent as occurswith the abrupt expansion. More of the gas molecules remain tightlybonded to the liquid, and as a result, the gas remains in the liquidlonger. This property is especially evident when the gas-enriched liquidis filled into a container such as a tank. When stored in suchcontainers even over long periods of time, for example several weeks,the gas is not liberated. The gas is also not liberated when the liquidis transported in such containers and exposed to jarring motions.

In this preferred embodiment, the pressure in the lower pressure systemhaving the outlet is reduced to a pressure of, for example, one bar. Thereduction in pressure to this level ensures the slow expansion of theliquid with only a small-scale release of the gas dissolved therein. Thepressure in this system can be reduced until it closely corresponds tothe external or atmospheric pressure outside of the pressure system. Thesystem is then effectively depressurized. Under these static conditions,the liquid can then be conducted out of the pressure system and filledinto containers such as tanks. Once the pressure vessel is emptied, itmay again be subjected to the elevated pressure level of the closedoverpressure system and refilled with more gas-enriched liquid from thatfirst phase of the process. In effect, the pressure system having anoutlet operates as a pressure lock that enables transfer of portions ofthe liquid volume out of the closed pressure system into a system, whichexposes the gas-enriched liquid to a pressure gradient, therebystabilizing the fluid system. As a result, the amount of free gascontained in the liquid product is increased.

In another aspect of this embodiment, the apparatus includes a reservoircontainer for holding a liquid, which is connected to a high-pressuregas supply line to form a closed overpressure system. Closure orblocking mechanisms, such as sliding valves, are provided in the linesconnecting the reservoir container and the gas supply source.

The reservoir container is further connected to conduct gas-enrichedliquid to a chamber having a pressure that is lower in comparison to thereservoir container, which connection can be opened and closedselectively. A pressure regulator at the high-pressure gas supply can beused to adjust the pressure in the closed overpressure system.

According to another aspect of the apparatus, a lower portion of thecontainer holds the liquid and the gas is supplied to an upper portionof the container. An external enrichment arrangement in the form of aclosed loop is provided, having a first line connected to the containerfor drawing gas from the upper portion; a second line connected to thecontainer for drawing liquid from the lower portion; a junction forcombining the first and second lines into a common line carrying bothliquid and gas; a supply device for receiving the liquid and gas fromthe common line and performing a first mixing to form a gas-enrichedliquid; and a swirling device connected to an output of the supplydevice for performing a second mixing and providing gas-enriched liquidback to the container at an upper portion thereof.

Instead of the external enrichment arrangement closed loop where theliquid is enriched with gas outside the reservoir container, an internalenrichment device, i.e., internal to the container, may be provided,according to an alternate embodiment. Likewise, there could be separatecontainers for unenriched liquid and the gas-enriched liquid instead ofthe one container, according to an alternative embodiment.

According to further aspects of the invention, the supply device is acentrifugal pump, the swirling device is a cyclone swirling chamber inwhich a net, screen or the like can be additionally installed, and thecontainer has an overpressure release valve at a top thereof. Thecentrifugal pump may include a high-pressure injector.

According to another aspect of the invention, adjustable valves, e.g.,sliding valves, are provided on the first line, the second line andbetween the swirling device and the container, to control the flow ofgas, liquid and gas-enriched liquid through the enrichment arrangementclosed loop. Pressure sensing devices, pressure sensors, are alsoprovided in the common line and at the output of the supply device, forexample, as well as at the container, for sensing the respectivepressures. Adjustment of the valves may also be used to obtain thedesired pressures as measured by the pressure sensors.

According to a further aspect of the invention, the chamber having apressure that is lower in comparison to the reservoir containercomprises a hollow ball valve, having slot-shaped openings which can beopened and closed, on a line leading from the container to the chamber.A pressure sensor measures the pressure inside the hollow ball valve.Pressure and flow speed sensors are provided at an outlet from thehollow ball valve, along with a gas measurement sensor for detecting theamount of free gas in liquid thereat.

The sensors and valves may form part of an automatic control systemoperated by a digital computer, for example, whereby desired levels ofgas-enrichment may be set and conveniently monitored, based on pressuresand flows in the apparatus. Alternatively, the system may be manuallyadjusted by manual actuation of the valves based on manual reading ofthe sensor' indications.

According to an aspect of the invention, the gas and the liquid aremixed in the supply device, and in the process, the liquid is enrichedwith the gas in the above-described manner, such that the gas is bondedto the liquid. That is, a measurably high concentration of “free” gas inthe liquid has not yet been attained. The gas-enriched liquid isreturned to the reservoir container following the mixing process. Thechamber in which the dominating pressure is lower is comparison to thereservoir container is connected to the reservoir container to receiveliquid therefrom. The connection is embodied such that it can be openedand closed. When opened, gas-enriched liquid exits the reservoircontainer and enters the chamber due to the different pressure ratios.The gas-enriched liquid is expanded according to the invention, and thegas that was previously bonded in the liquid is freed.

Another preferred embodiment of the invention is characterized by anapparatus in which the liquid is moved from the closed overpressuresystem into a lower pressure system comprising a series of pressurereduction containers used to lower the pressure of the gas-enrichedliquid. This embodiment comprises a supply device for supplying the gasto the liquid, a reservoir for the gas-enriched liquid; and a connectionbetween the reservoir and the supply device to form a closedoverpressure system. In addition, the lower pressure system includes atleast one pressure reduction vessel or container whose internalpressures can be set at different levels to create a pressure gradientover the direction of flow of the gas-enriched liquid. Each of thepressure reduction containers may be closed or otherwise controlled witha cut-off mechanism.

In this embodiment, the lower region of the first pressure reductioncontainer is connected to the reservoir container to allow passage ofthe gas-enriched liquid. this connection is fitted with a closure meansthat allows the passage of the gas-enriched liquid to be controller orblocked. The liquid level in the reservoir container is maintained at avolume level that is higher than the level in the pressure container.The difference in hydrostatic pressure allows movement of thegas-enriched liquid from the reservoir container to the pressurereduction container. This is advantageous in that a pump or othermotion-based device is not required to move the liquid.

As the gas-enriched liquid moves through the system, the conditions inthe pressure reduction container are maintained so as to prevent adecrease in pressure, which would result in release of the gas. Tomaintain these static conditions, the pressure reduction container isdirectly connected to the source of the gas, for example an external gastank as previously described. This gas supply source is an integralcomponent of the closed overpressure system, which also includes thereservoir container. The connection to the gas supply source provides ameans of equalizing the pressure between the reservoir container and thepressure reduction container before the gas-enriched liquid is movedinto the pressure reduction container. Once this equal pressure has beenestablished, the connection to the gas supply source is closed, and theblock between the reservoir container and the pressure reductioncontainer is removed. Because of the difference in volume levels, aportion of the liquid in the reservoir container is transported byhydrostatic pressure out into the pressure reduction container. Thisliquid is advantageously not subject to any changes in pressure duringthis transfer process, and therefore no bound gas in the liquid isrelease.

After the pressure reduction vessel is filled, the input connection fromthe reservoir vessel is closed, and the gradual pressure reductionbegins. A pressure discharge valve is preferably situated in thepressure reduction container, most preferably in the upper region. Thispressure discharge valve is used to reduce the overpressure in thepressure reduction container at a slow, incremental pace. A manometermay be disposed within the pressure reduction container to monitor therate of pressure change.

The pressure reduction container is further equipped with a liquidoutlet to allow collection of the gas-enriched liquid into storagecontainers once the pressure in the pressure reduction container hasbeen reduced to atmospheric pressure.

In a further preferred embodiment, the reservoir container and the gassupply of the overpressure system may be connected to a lower pressuresystem comprising a series of two pressure reduction containers. Theseare in turn connected to each other by a gas-pressure equalization line,which can be blocked by means of a pressure discharge valve.

Gas and gas-enriched liquid can thus alternately be supplied from eitherthe reservoir container or the gas supply into either of these pressurereduction containers. By using this series of pressure reductionvessels, the volume of liquid that can be processed by the apparatusesof the invention is increased significantly.

In another aspect of this embodiment, a liquid-level regulating deviceis provided to monitor the level of the gas-enriched liquid in thereservoir container. This device is advantageously used to ensure that asufficient liquid volume is always present in the reservoir container,to permit continuous filling of the one or more pressure reductioncontainers according to the invention.

Alternatively, more than two pressure reduction containers may be usedin sequence. The volume capacity of the reservoir container shouldhowever be of a correspondingly increased dimension to provide adequateinput to the pressure reduction vessels. Transfer of the gas-enrichedliquid through the system of pressure reduction vessels is accomplishedin stepwise fashion. The first vessel is brought to the same pressure asthe reservoir container by introduction of the supply gas, and is thenfilled with liquid. The pressurized gas fills the headspace above theliquid in the pressure reduction vessel. Any free headspace gas presentin this first pressure reduction vessel as a result of the overpressurein the reservoir is then introduced to the next pressure reductionvessel in the series via the gas-equalization line when the pressuredischarge valve is opened. An advantage of this arrangement is that noadditional supply of gas is necessary for building the pressure in theremaining pressure reduction vessels in the sequence once the pressurehas been adjusted in the first vessel. Rather, gas that has been used inone of the pressure reduction vessels can also be used in the otherpressure reduction vessels, thereby enabling consumption of gas to bemaximized.

The apparatus of the invention can preferably be operated continuously,thereby allowing continuous removal of gas-enriched liquid from the oneor more pressure reduction containers.

Regardless of which embodiment of the pressure-adjusting apparatus isused, the reservoir container may be embodied as a tank, for example,that is initially filled, in the absence of pressure, to about ⅔capacity with the liquid. The gas intended to enrich the liquid isintroduced into the upper third of the tank. The gas is introduced underhigh pressure, and the tank, along with adjacent enrichment components,form a closed overpressure system. Water, for example, is used as theliquid, and oxygen supplied from a commercially available, high-pressureoxygen source is supplied as the gas. The pressure in the closedoverpressure system can be adjusted with a pressure regulator providedat the oxygen source, as well as with a pressure relief valve providedon the reservoir container tank.

As mentioned above, the liquid and the gas can be mixed by, for example,a supply device disposed in the container. However, in the preferredembodiment, the reservoir container is connected via a closed loopsystem to conduct liquid and gas to an external supply device, in whichthey are mixed together, resulting in the bonded enrichment of theliquid with the gas. As already mentioned, in an embodiment, the supplydevice is preferably a centrifugal pump having a high-pressure injector,which is connected via a closed loop system to the reservoir container.A centrifugal pump having a high-pressure injector is capable ofsuctioning and further conducting a gas in addition to a liquid, or aliquid/gas mixture. The centrifugal pump suctions liquid and gas, andswirls them together as they pass quickly through the pump. Thus, theliquid is enriched with the gas, but this is a bonded enrichment; inother words, a close (strong) bonding of the gas to the liquid isachieved.

According to an aspect of the invention, on the suctioning side of thecentrifugal pump, the loop system includes a gas line that exits theupper region of the reservoir container, and a liquid line that exitsthe lower region of the reservoir container, the lines being guided to acommon line directly in front of the centrifugal pump. The gas line andthe liquid line are connected to the reservoir container such that theycan remove gas and liquid, respectively, from the different regions ofthe reservoir container. Because these lines are guided together to acommon line, a liquid/gas mixture is supplied to the centrifugal pump. Avacuum is simultaneously formed in the gas line, for example, due to thesuction of the liquid through the centrifugal pump. A suction of the gasthrough the centrifugal pump is therefore simultaneously achieved. Onthe discharge side of the centrifugal pump, a swirling device may bedisposed in a line between the centrifugal pump and the reservoircontainer. A further mixing of liquid and gas can advantageously beachieved with the swirling device. A cyclone swirling chamber, forexample, in which a net, a screen or the like can additionally beinstalled, can be used as a swirling device. As the gas-enriched liquidpasses through the device, it is swirled, effecting further mixing ofthe liquid and the gas. An advantage of this embodiment is that thedegree of enrichment of the gas in the liquid is increased. The swirlingdevice simultaneously represents a pressure-reducing device. While avacuum exists on the suction side of the supply device, causing themedia of gas and liquid to be auctioned into the supply device, anoverpressure exists on the other side of the supply device. Thisoverpressure can be reduced in the swirling device. This is achieved,for example, by an effective widening of the cross section of the linebetween the supply device and the container in the swirling device.

According to an exemplary embodiment of the invention, the chamberhaving a lower pressure than the reservoir container comprises a hollowball valve that is disposed in a line for gas-enriched liquid leadingout of the reservoir container. The interior of the hollow ball valveforms a pressure system having an outlet. Inside its hollow ball, thehollow ball valve has a space in which a specific pressure can berealized, thereby allowing the ball to open or close the valve outlet.The pressure dominating here is significantly less than the pressure inthe overpressure system of the reservoir container. The pressure drop isachieved because when the valve is in the closed position, the interiorof the hollow ball valve is cut off from overpressure system. To allowentry of the gas-enriched liquid, the hollow ball valve is only openedslightly, forming a very narrow, nozzle-shaped opening. The openings forthe passage of the liquid, which are formed between the interior of thehollow ball valve and the lines that lead away when the valve opens, arepreferably slot-shaped. Because of this slot-shaped feature, the liquidis forced rapidly into the interior of the hollow ball valve under highpressure. The gas-enriched liquid enters the interior of which is undera substantially lower pressure, and can expand abruptly. According tothe invention, during this expansion, the gas that was previously bondedto the liquid is converted into “free” gas in the liquid. This free gasin the liquid is a physically bonded gas that nevertheless forms nochemical compound with the molecules of the liquid, and is therefore“free”. The hollow ball valve can be opened to a greater or lesserextent, which widens the slot-like opening between the interior ofhollow ball valve and the lines leading away, so the pressure inside thehollow ball valve can thereby be set directly. To monitor the pressure,a pressure sensor (manometer) is also preferably disposed inside thehollow ball valve. A pressure sensor that measures and indicates thepressure dominating in the reservoir container is preferably associatedwith the reservoir container, as well.

In a preferred embodiment, a flow-speed measurement device is disposedin a line that carries away gas-enriched liquid, downstream of thehollow ball valve in the flow direction of the liquid. In addition tothe different pressures in the reservoir container and the inside of thehollow ball valve, the flow speed of the liquid through the hollow ballvalve is a variable on which the concentration of the free gas in theliquid is dependent. This flow speed is monitored with the flow-speedmeasuring device. The value of the flow speed is a function of the setpressures and the size of the openings. Moreover, a gas measurementdevice, with which the concentration of free gas in the gas-enrichedliquid can be measured and monitored, is disposed in the line thatcarries away the gas-enriched liquid, downstream of the hollow ballvalve in the flow direction of the liquid. For optimum measurement bythis gas measurement device, a specific liquid flow speed is set, whichis monitored with the flow-speed measurement device.

A line leading out of the hollow ball valve terminates in an outlet thatcan be opened and closed, and out of which liquid enriched with free gascan be removed. The liquid is drawn off, for example, intodiffusion-tight containers.

A gas-enriched liquid, in particular, water enriched with oxygen, whichcan be produced by the exemplary method and apparatus according to theinvention, is advantageously characterized by a concentration of freegas of over 60 mg/L. In particular, water enriched in accordance withthe invention may have a concentration of free oxygen of over 140 mg/L,and most particularly over 200 mg/L.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 illustrates an exemplary embodiment of an apparatus according tothe invention for enriching a liquid with a gas.

FIG. 2 illustrates the serial pressure reduction apparatus comprisingthe lower pressure system that is an alternate embodiment of theinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The invention will now be described in more detail by way of examplewith reference to the embodiment shown in the accompanying figure. Itshould be kept in mind that the following described embodiment is onlypresented by way of example and should not be construed as limiting theinventive concept to any particular physical configuration.

The apparatus illustrated in FIG. 1 comprises a closed reservoircontainer 1 for holding a gas-enriched liquid 2. Reservoir container 1is provided with a pressure sensing and indicating device (manometer) 3for displaying the pressure in reservoir container 1, and with anoverpressure valve 4. Reservoir container 1 is connected to anenrichment arrangement, a closed loop system for enriching a liquid witha gas. The enrichment loop includes a supply device 5 for mixing a gaswith a liquid. Supply device 5 comprises, for example, a centrifugalpump. On the intake side of the centrifugal pump supply device 5, acommon line having a manometer 3 is provided for feeding a liquid and agas to the pump 5 from the reservoir container 1. Gas line 6 leads awayfrom the upper region of reservoir container 1, and liquid line 7 leadsaway from the lower region of reservoir container 1, these lines joiningat the common line feeding the supply device 5 immediately upstream ofsupply device 5 in the flow direction. An adjustable slide valve 8 isdisposed in liquid line 7, upstream of the joining point with gas line6, and an adjustable slide valve 8 is provided in gas line 6, upstreamof the joining point with liquid line 7.

A line 9 for a gas/liquid mixture leads back to reservoir container 1from supply device 5, so that the supply device 5 is disposed in aclosed loop. A swirling device 19 is disposed in line 9 between thesupply device 5 and the reservoir container 1. This swirling device 19can be, for example, a cyclone swirling chamber. A slide valve 8 islikewise disposed in line 9 downstream of the swirling device 19.

The gas that is used to enrich the liquid is stored in the upper regionof reservoir container 1. The gas can be introduced into reservoircontainer 1 via a line 11 from an external gas tank 10, for example. Gastank 10 is a high-pressure gas tank having a pressure regulator 12 inline 11 at the outlet of the tank 10. The pressure of the gas inreservoir container 1, and therefore the closed system formed byreservoir system 1, supply device 5 and lines 6, 7 and 9, can be set toa desired overpressure value (e.g., a pressure greater than atmosphericpressure) with pressure regulator 12. For example, a pressure of 1.5 to6.0 bars may be set. Overpressure relief valve 4 on container 1 alsoserves to control the pressure in the container 1 by preventing thepressure from exceeding a certain set value, for example.

A line 13 for carrying gas-enriched liquid away from the reservoircontainer 1 is connected to the lower region of reservoir container 1.Line 13 leads to a chamber 14 in which the dominating pressure is lowerthan the dominating pressure in the reservoir container 1. This chamberis embodied by a schematically-illustrated hollow ball valve 14, forexample, which is inserted into line 13. A manometer 3 associated withhollow ball valve 14 measures the pressure inside hollow ball valve 14.

Further components are disposed in line 13, downstream of hollow ballvalve 14 in the flow direction. In particular, a flow-speed measurementdevice 15 and the sensor 16 of a gas-measurement device 17 are disposedin line 13. Line 13 ultimately terminates in an outlet 18, with which amanometer 3 and a slide valve 8 are associated.

The apparatus shown in the drawing is used for enriching a liquid with agas according to the following method. A quantity of water is suppliedto the container 1 absent pressure to a level of, for example,two-thirds full. The gas is then supplied to container 1 to establish anoverpressure environment therein to a pre-selected pressure. The gas andliquid now stored in reservoir container 1 at a selected overpressureare supplied via lines 6 and 7, respectively, to the common line andthereby to supply device 5. The two media, liquid and gas, are mixed insupply device 5. In the process, the liquid is enriched with the gassuch that the gas is bonded to the liquid. The concentration of freegas, that is, only physically-bonded gas, in the liquid, however, isstill low at this point. The liquid and gas are mixed further in theswirling device 19 disposed in line 9, and the further mixed liquid andgas is supplied back to reservoir container 1. In this way, the liquidand gas are mixed in a closed loop overpressure system comprising thereservoir container 1, the supply device 5, the swirling device 19, andlines 6, 7 and 9. Since the system is closed, any excess gas which doesnot bond with the liquid will be advantageously contained in container 1and be usable for further enrichment according to an object of theinvention.

Subsequent to enrichment through the closed loop overpressure system,liquid 2 enriched with bonded gas is provided to the interior of hollowball valve 14 via line 13. The liquid 2 is forced at high pressurethrough slot-like, narrow openings between the interior of hollow ballvalve 14 and line 13, as a result of the different pressures inreservoir container 1 and hollow ball valve 14. As the gas-enriched(bonded) liquid 2 enters the lower pressure interior of hollow ballvalve 14, it expands abruptly, thereby freeing the gas bonded in theliquid 2. Because of the abrupt expansion, concentrations of free gas inliquid 2 of over 60 mg/L can be attained.

For example, if water is enriched with oxygen, a concentration over 200mg/l can be achieved according to the above-described apparatus andmethod. The expansion in hollow ball valve 14 is monitored by flow-speedmeasurement device 15 and the gas concentration is monitored bygas-measurement device 17 with sensor 16. The liquid enriched with freegas can be removed from the apparatus at outlet 18, and, for example,can be drawn off into transportable containers.

FIG. 2 shows an alternative exemplary embodiment of an apparatus forexecuting the method of this invention, which incorporates at least onepressure-reduction container. In this embodiment, pressure-reductioncontainers 119 and 119′ are disposed downstream of the reservoircontainer 1 (not shown in FIG. 2). Both containers are connected to thereservoir container by way of liquid flow line 13, which terminates inthe lower region of each container. Gas line 6′ is connected to thereservoir container 1, and further connects the upper regions of thepressure reduction vessels 119 and 119′ to permit gas flow between them.Sliding valves 8 are inserted into both liquid flow line 13 and gas flowline 6′ as blocking elements for flow control. Liquid flow line 13includes a branch 13′, which leads to the second pressure reductioncontainer 119′. This branch establishes a liquid conducting connectionbetween the second pressure reduction container 119′ and the reservoircontainer 1. This connection is maintained even if the liquid-conductingconnection between the first pressure reduction container 119′ andreservoir container 1 is broken by operation of the respective slidingvalve 8. Line 13 terminates in an outlet 18.

The two pressure reduction containers 119, 119′ are also connected toone another, by way of a gas equalizer line 20, so as to conduct gas.Gas equalizer line 20 terminates in the upper region of each of thepressure reduction containers 119 and 119′, respectively. A slidingvalve 8 and a gas flow-through indicator 23 are disposed in the gasequalizer line 20. In addition, each pressure-reduction container 119and 119′ has a pressure-discharge valve 22 in this upper region.

The two pressure reduction containers 119 and 119′ are disposedspatially below the height of the liquid level in reservoir container 1.

In this alternative embodiment as is shown in FIG. 2., it is intendedthat the release of gas in the liquid be prevented. In contrast to thefirst embodiment of the invention, the gas dissolved in the liquid isnot to be released during the expansion of the liquid. Here, the gas isallowed to remain bonded to the liquid, so the liquid is particularlystable after it has been filled into containers and during transport.

In this alternative embodiment, the reservoir container 1 (not shown) isunder a specific overpressure. When the sliding valve 8 is opened, thefirst pressure reduction container 119 is filled with a gas by way ofgas line 6′, and thus brought under the same overpressure. The pressureratios are read using manometer 3. After this pressure has beengenerated, the sliding valve 8 in gas line 6′ is again closed. Thesliding valves 8 in line 13 are then opened. Because of the hydrostaticpressure and the arrangement of pressure-reduction container 119 belowthe height of the liquid level in reservoir container 1, liquid 2 flowsthrough line 13 into the first pressure reduction container 119. Theliquid flows into this pressure reduction container 119 until an equalliquid level is attained between reservoir container 1 and pressurereduction container 119, with residual gas preferably remaining in thepressure reduction container 119.

Afterward, sliding valves 8 in line 13 are again closed. When slidingvalve 8 in the upper region of container 119 is open, the gas that isstill present is conducted out of this container and into the secondpressure-reduction container 119′ by way of gas-equalizer line 20. Whilethe gas is being carried off, the pressure drops in the firstpressure-reduction container 119. The gas is carried off slowly andincrementally, so the pressure reduction is effected in acorrespondingly slow fashion. An abrupt expansion of the liquid inpressure-reduction container 119 is prevented; instead, the liquidexpands slowly. The gas escapes from pressure-reduction container 119until the desired low pressure has been established in this container.Sliding valve 8 in gas-equalizer line 20 is then closed, and the slidingvalves 8 provided in line 13 between pressure-reduction container 119and outlet valve 18 are opened. The liquid can now be carried off viaoutlet 18 and, for example, filled into tanks.

While the liquid is being carried off from pressure-reduction container19, pressure reduction container 119′ is simultaneously filled withliquid from reservoir container 1 in a corresponding manner. Previously,this pressure-reduction container 119′ has been brought under the samehigh pressure as in reservoir container 1 with the gas frompressure-reduction container 119 and, possibly, with additional gas, viagas line 6′. Liquid is subsequently introduced into pressure-reductioncontainer 119′ via branch 13′. To reduce the pressure in thispressure-reduction container 119′, gas-equalizer line 20 is re-opened,whereupon gas remaining in pressure-reduction container 119 can beintroduced into the first pressure-reduction container 119.

These alternating steps of filling and emptying the pressure-reductioncontainers 119, 119′ can be effected continuously. This permits acontinuous removal of liquid at outlet 18. A liquid-level regulatingdevice, not shown in detail, in reservoir container 1 ensures that aliquid level necessary for producing the necessary hydrostatic pressureratios is always present in reservoir container 1.

With a corresponding increase in the volume of reservoir container 1,further pressure-reduction containers similar 119, and 119′ can beprovided.

The operation may be performed manually, or under the control of aautomatic control system including a digital computer, for example, aswould be apparent to one skilled in the art. It will be apparent to oneskilled in the art that the manner of making and using the claimedinvention has been adequately disclosed in the above-written descriptionof the preferred embodiment taken together with the drawing.

It will be understood that the above described preferred embodiment ofthe present invention is susceptible to various modifications, changes,and adaptations, and the same are intended to be comprehended within themeaning and range of equivalents of the appended claims.

For example, instead of the external enrichment arrangement, an internalto the container enrichment arrangement could be used. Further, besidesthe hollow ball valve, other ways could be used for effecting the abruptpressure drop, as would be apparent to one skilled in the art.

What is claimed is:
 1. A method of making a liquid enriched with a highconcentration of dissolved gas, comprising: a. providing a closedreservoir container with a quantity of liquid to a pre-selected level;b. providing a quantity of pressurized gas to the closed reservoircontainer to establish a pre-selected pressure within the container; c.enriching the liquid in the closed reservoir container with thepressurized gas using a mixing device, to form a gas-enriched liquidhaving gas molecules physically bonded to the liquid; and d. expandingthe gas-enriched liquid in a lower pressure system comprising a seriesof pressure reduction vessels, such that the pressure in the series ofpressure reduction vessels is initially equal to that of the closedreservoir and is subsequently reduced in slow incremental fashion,thereby forming a liquid enriched with a high concentration of dissolvedgas; wherein the method further comprises transporting the gas-enrichedliquid from a first pressure reduction vessel into another pressurereduction vessel in the series, maintaining the same pressure in therespective pressure vessels during transport; wherein the initialpressure in the first one of the pressure reduction vessels in theseries is created by the flow of an overpressure of gas from the closedreservoir container into the first pressure reduction vessel; andwherein the flow of an overpressure of gas into the first one of thepressure reduction vessels in the series is closed off from the closedreservoir container, and the overpressure of gas in the first pressurereduction vessel is subsequently directed through an outlet to a nextpressure reduction vessel in the series.
 2. The method of claim 1,wherein the pressure in the lower pressure system is reduced to a finalpressure of about one bar.
 3. The method of claim 1, wherein thepressure in the lower pressure system is reduced to a final pressurewhich is equal to the pressure of the external environment.
 4. Themethod of claim 1, wherein the initial pressure of gas in the first oneof the pressure reduction vessels in the series is equal to the pressurein the closed reservoir container, this pressure being subsequentlyreduced in slow in incremental fashion to allow expansion of thegas-enriched liquid.
 5. The method of claim 1, wherein the overpressureof gas from each pressure reduction vessel in the series of pressurereduction vessels is directed through an outlet to a next vessel in theseries.
 6. The method of claim 5, wherein the pressure in a pressurereduction vessel in the series of pressure reduction vessels is reducedto a final pressure of about one bar.
 7. The method of claim 5, whereinthe pressure in the final pressure reduction vessel in the series ofpressure reduction vessels is reduced to a final pressure which is equalto the pressure of an external environment.